The present application claims priority based on Japanese Application No. 2006-302263 filed on Nov. 8, 2006.
Conventionally, inorganic or organic copper agents, and antibiotics such as kasugamycin, streptomycin and oxytetracycline are used against bacterial diseases in various agricultural and horticultural crops. In addition, oxolinic acid was registered in 1989 as a synthetic antibacterial agent and has largely contributed to the increase of crop production. However, inorganic and organic copper agents tend to cause crop injury to agricultural and horticultural crops, so that timing and target crops are restricted in using the inorganic and organic agents. Further, antibiotics have drawbacks in that as a result of continuously using an antibiotic, the bacterial pathogen gains resistance to the antibiotic. With respect to oxolinic acid as well, the resistant bacteria has emerged recently and its use is restricted.
Therefore, in order to overcome the problems of crop injuries and resistant bacteria, there has been an increased interest in biological pesticides as a means for substituting for conventional synthetic fungicides or as a means for using in combination with the conventional synthetic fungicides. Biological pesticides are advantageous in that they cause very little environmental pollution, harmonize with ecosystem, and are superior in the controlling effect as compared to conventional synthetic fungicides. Those known as a microbial agrochemical used for controlling bacterial disease in agricultural and horticultural crops include, for example, non-pathogenic Erwinia carotovora particularly used for controlling bacterial soft rot of leaf and root vegetables; and Pseudomonas sp. CAB-02 or Trichoderma atroviride particularly used for controlling bacterial grain rot and bacterial seedling blight, that are contagious bacterial diseases in rice seeds. Bactericidal compositions for agriculture and horticulture containing such microorganism have been developed and marketed. Further, Patent document 1 describes Pseudomonas fluorescens strain G7090 having controlling effect against Pseudomonas cichorii which is a causal bacterium of bacterial rot of lettuce.
Microbial agrochemicals, however, generally target only restricted number of plant diseases and often do not exert satisfactory effect against other plant diseases. For example, non-pathogenic Erwinia carotovora only targets bacterial soft rot of leaf and root vegetables, Pseudomonas sp. CAB-02 or Trichoderma atroviride only targets rice diseases, and Pseudomonas fluorescens only targets bacterial rot of lettuce. As such, target diseases are restricted and almost no effect can be expected for other bacterial diseases. Further, because pathogenic Erwinia carotovora is controlled by bacteriocin which is an antibacterial protein produced by non-pathogenic Erwinia carotovora, it is concerned that non-pathogenic Erwinia carotovora may acquire resistance to bacteriocin (e.g., non-patent reference 1).    Patent Reference 1: Japanese Laid-Open Patent Application No.    Non-patent Reference 1: Biological control of crop diseases by antagonistic microorganisms, III-5, Control of vegetable bacterial soft rot by non-pathogenic Erwinia carotovora, Kumiai Chemical Industry Co. Ltd., 65-76: 2003